A. Field of the Invention
The present invention is an image information reading device, especially to a wide image scanner which can scan the image of a large scale original using only an image sensor of a regular size.
B. Description of the Prior Art
A conventional scanner is designed for the most commonly used size of documents, such as A4, A3, B4, or even B3 sizes. The width of an image reading device, such as a Charge Coupled Device (CCD) or a Contact Image Sensor (CIS), is also designed wide enough to finish reading the image of the regular-sized original in a single pass. For scanning large scale sheets, such as posters or newspapers, the user would have to manually operate the scanner to scan the original portion by portion. Then, after the image of the entire original has been scanned, the user has to merge corresponding portions together by an application software. Such procedure is very tedious and time consuming. On the other hand, if the user would like to scan the large-scaled original in a single pass, the width of the image reading device must be wide enough to cover the width of the original. However, since such wide image reading device is very expensive, the implementation cost for the entire scanner will be very high.
Accordingly, it is an object of the present invention to provide a wide image scanner which can read a large scale original using a regular-sized image reading device, thereby to reduce the implementation cost.
It is another object of the present invention to provide a structure and mechanism for a wide image scanner which can automatically determine the number of passes for scanning the entire image of the original portion by portion without human operation.
In accordance with the present invention, the preferred embodiment of the present invention preferably includes a sliding shaft, an image reading device, a number of width sensors, a paper edge sensor, and a control module. On one side of the housing, there is a paper feeding opening for inputting an original. Inside the housing and close to the paper feeding opening, there is a set of rollers cooperating to form a nip so as to allow the original to pass therebetween. On the opposite side of the housing, there is a paper output opening for the original to output. Inside the housing and close to the paper output opening, there is the other set of rollers cooperating to form a nip for the original to pass through. A transparent sheet supporting plate is disposed on the same horizontal plane of the nips of the rollers to support the sheet while the sheet is driven back and forth by the two sets of rollers. An image reading device is mounted on a sliding shaft and below the transparent sheet supporting plate for reading the image of the original line by line.
At one side of the housing, there is a paper edge sensor for detecting the end edge of the origin. When detecting the end edge of the origin, the paper edge sensor generates a vertical control signal to a control module. Upon receiving the vertical control signal, the control module will enable the two sets of rollers to rotate in an opposite direction. While the origin is fed into the housing, the paper width sensors located on the inner top of the housing detect the side edge of the original and generate horizontal control signals to the control module. Upon receiving the horizontal control signals, the control module will set the number of horizontal displacement times and then enable the driving device to move the image reading device to a next displacement position every time when the origin is driven to an end. The procedure continues until the image reading device has been moved to a final displacement position predetermined by the horizontal control signal. Consequently, the entire image of the origin can automatically be read portion by portion without manual operation.